Journal bearing and rotary machine

Abstract

A journal bearing including a plurality of bearing pads having pad surfaces which configured to slidably come into contact with an outer circumferential surface of a rotating shaft and disposed at intervals, a key member provided a part of a pad rear surface which faces radially outward in the bearing pad, having a curved surface which is curved around an axis parallel to the central axis, configured to extend to have the same cross-sectional shape, and formed of a material having a hardness higher than that of a material forming the pad rear surface of the bearing pad, and a housing having a support surface in contact with a part of the curved surface of the key member in the circumferential direction and configured to support the key member and the bearing pad to be swingable from an outer side in a radial direction.

What is claimed is: 
     
       1. A journal bearing comprising:
 a plurality of bearing pads having pad surfaces configured to slidably come into contact with an outer circumferential surface of a rotating shaft and disposed at intervals in a circumferential direction around a central axis; 
 a key member provided at a part of a pad rear surface which faces radially outward of the bearing pad, the key member having a curved surface which is curved around an axis parallel to the central axis, the key member being formed of a material having a hardness higher than that of a material forming the pad rear surface of the bearing pad; and 
 a housing having a support surface, which is curved around the central axis, in line contact with a part of the curved surface of the key member in the circumferential direction in a direction of the central axis in which the central axis extends, the housing being configured to support the key member and the bearing pad to be swingable from an outer side in a radial direction of the key member and the bearing pad, 
 wherein the key member has a rectangular shape extending in the direction of the central axis when viewed in the radial direction, 
 the key member is fixed to the pad rear surface by performing punching at a plurality of portions of the key member on a boundary with the pad rear surface, 
 a length of the key member in the direction of the central axis is shorter than a length of the bearing pad in the direction of the central axis, 
 a curvature radius of the curved surface is less than a curvature radius of the support surface, 
 the curved surface is formed continuously in the direction of the central axis with a same shape and the same curvature radius, and 
 the curved surface is continuously formed with the same width between one portion and another portion, which is adjacent to the one portion in the direction of the central axis, of the plurality of portions. 
 
     
     
       2. The journal bearing according to  claim 1 ,
 wherein the bearing pad has a key member mounting surface orthogonal to the radial direction, and 
 the key member has a fixed surface which faces the key member mounting surface and is orthogonal to the radial direction. 
 
     
     
       3. The journal bearing according to  claim 2 ,
 wherein only the curved surface configures to be in contact with the support surface of the housing when the key member and the bearing pad swing. 
 
     
     
       4. The journal bearing according to  claim 3 , further comprising
 a concave portion formed in the curved surface of the key member and recessed radially inward at an intermediate position of the curved surface in the circumferential direction, and 
 a positioning member configured to protrude radially inward from the support surface and fixed to the key member in a state in which it is inserted into the concave portion. 
 
     
     
       5. The journal bearing according to  claim 2 , further comprising
 a concave portion formed in the curved surface of the key member and recessed radially inward at an intermediate position of the curved surface in the circumferential direction, and 
 a positioning member configured to protrude radially inward from the support surface and fixed to the key member in a state in which it is inserted into the concave portion. 
 
     
     
       6. The journal bearing according to  claim 1 ,
 wherein only the curved surface configures to be in contact with the support surface of the housing when the key member and the bearing pad swing. 
 
     
     
       7. The journal bearing according to  claim 6 , further comprising
 a concave portion formed in the curved surface of the key member and recessed radially inward at an intermediate position of the curved surface in the circumferential direction, and 
 a positioning member configured to protrude radially inward from the support surface and fixed to the key member in a state in which it is inserted into the concave portion. 
 
     
     
       8. The journal bearing according to  claim 1 , further comprising
 a concave portion formed in the curved surface of the key member and recessed radially inward at an intermediate position of the curved surface in the circumferential direction, and 
 a positioning member configured to protrude radially inward from the support surface and fixed to the key member in a state in which it is inserted into the concave portion. 
 
     
     
       9. The journal bearing according to  claim 1 , wherein the curved surface of the key member and the pad rear surface of the bearing pad have the same curvature radius in the circumferential direction. 
     
     
       10. The journal bearing according to  claim 1 , wherein the curved surface of the key member has a smaller curvature radius in the circumferential direction than the pad rear surface of the bearing pad. 
     
     
       11. A rotary machine comprising:
 a rotating shaft; and 
 a journal bearing according to  claim 1  which supports the rotating shaft.